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Constants clash on pi day

By Jacob Aron

Feeling a little more circular than usual today? That’s because 14 March, which is 3.14 in the US date format, is pi day. Enjoy this year’s festivities, for dark clouds may be gathering on the horizon for this popular constant.

Pies and other round consumables are the obvious choice of food for celebrating pi day, so be sure to enter the Pi Day Baking Challenge. But what gift should you bring for your host? One option is the Radian Watch, which tells the time in terms of pi, although anything circular may be well received.

Pi party attendees will be expected to know a few facts about the famous ratio. This video from maths author Alex Bellos and University of Nottingham physicist Roger Bowley will help you brush up. Those already in the know can celebrate with a spot of brain-teasing from the Pi Day Challenge, a series of puzzles devised by a team of logicians.

For an even greater mental workout you could try memorising the digits of pi – though clearly not all 10 trillion known, calculated by Alexander Yee and Shigeru Kondo last year.

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Pi’s decimal representation goes on forever, which means that the complete works of Shakespeare may be encoded in its digits, as mathematical artist Vi Hart explains in this video .

The end of pi?

The infinite expanse of pi also wedges the door open for another record attempt this year, but Yee, a computer scientist at University of Illinois at Urbana-Champaign, says he and Kondo have hit their limit. “In our 10 trillion digits computation, we were getting a hard drive failure every two weeks or so,” says Yee. “To reach 20 trillion, we need to implement better redundancy to elegantly handle and recover from hardware failures.”

So is this the end of pi as we know it? Yee is not aware of any others currently attempting to break 10 trillion, although it could be going on in secret. “A supercomputer can definitely do better, but I’m tempted to think that anyone approving such use of supercomputer time would have a decent chance of getting fired.”

One man who would love to see pi’s downfall is Michael Hartl, author of The Tau Manifesto, which calls for the famous constant to be replaced with tau, equal to 2 pi.

Since 2010, Hartl has used compelling arguments to convince others that tau is the more natural circle constant. He says that momentum for the change is growing&colon; “In any decent-sized collection of math geeks, the chances are close to 1 that someone has heard of tau.”